1. Field of the Invention
This invention relates to a method of simulating machining steps which is used to confirm NC (numerical control) programs. More particularly, this invention relates to a method of simulating the machining steps which are suitable for machining arbitrary cubic shapes.
2. Prior Art
A previous method of simulating machining steps graphically displays in animation on a display unit the process of machining a blank by tools and machines. Such a method can quickly and easily confirm the desirability of the machining sequence and can detect errors, if any, in an NC program before the machining is actually conducted, and can prevent defects in the machining or the collision of the machines, eliminate the necessity of idling, and improve the operational efficiency of the machines.
Machining simulation systems have been proposed which simulate a machining process by displaying in projections or sections a blank in the process of having its shape changed as the tool is moved. According to one such method, a three-dimensional space is divided into a given number of segments; a determination as to whether or not each segment has been filled by the blank is stored in a memory, and images are displayed in accordance with the stored data. However, this method is defective in that if the size of one segment is reduced, the memory capacity required for the data storage increases enormously and the processing for the change of the shape also becomes extensive such that an inexpensive processing system could not deal with them smoothly. Conversely, if the size of one segment is increased, the memory capacity for storing the blank shapes as well as the number of image processing steps may be reduced, but the images on display become so crude that details of the machining steps for the blank shape could not be understood.
As stated above, none of the prior art simulation methods for a machining center could provide a detailed display of how a blank is machined. Particularly, in the case of the simulated machining of a cubic shape, the amount of information to be stored generally becomes enormous, requiring an expensive system. In order to overcome the defects, there have been proposed methods to reduce the amount of information and processing needed. For instance, an X-Y plane is divided into grids and the height of a blank in the direction of a Z-axis at each point is stored in a memory. However, this method is defective in that as the expressing mode for the blank shapes in simulation differs from that for display, every time the blank is cut in the expressing mode for the simulation, it must be converted to the display mode. Further, it is defective in that if the blank has a cavity in the direction of the Z-axis, the method cannot express such a cavity.